October 06, 2016

Can tropical systems influence the spread of the Zika virus?

By By Katy Galimberti, AccuWeather.com Staff Writer

October 06, 2016, 6:55:56 AM EDT

Experts say that hurricanes and tropical storms could influence the spread of the Zika virus.

With Hurricane Matthew churning toward the U.S. East Coast, questions are rising if tropical activity could lead to a wider spread of the Aedes aegypti mosquitoes.

Jason Rasgon, associate professor of entomology and disease epidemiology at Penn State University, told AccuWeather that there are multiple methods in which hurricanes and tropical storms can spread mosquitoes, including those carrying Zika.

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Mosquitoes can be picked up and blown to a new area as the storm advances, he said. Mosquitoes are light and are mostly unaffected by raindrops.

If winds are too strong for the mosquitoes, they will "hunker down," Rasgon said, and avoid being entangled in a storm.

Though some mosquitoes could be transported, it is unlikely weather systems will be a major method of spreading Zika-carrying mosquitoes, Michael Bentley, staff entomologist for the National Pest Management Association told AccuWeather.

"The number of mosquitoes that would survive being transported by a powerful weather system would be very, very low," he said. "The likelihood that any of those surviving mosquitoes would be infected with Zika would be even lower and extremely doubtful."

The Centers for Disease Control and Prevention (CDC) echoed the low risk associated with natural disasters and the increased spread of mosquito-borne viruses.

"Hurricanes in the continental United States have rarely been accompanied by outbreaks of viruses spread by mosquitoes. Flooding immediately washed away existing mosquito larvae populations," Dr. Ben Beard, a CDC official, said.

The more serious threat is the potential impact to mosquito control efforts, Rasgon said. During a storm, insecticide spraying would be put on halt. Rain can also wash away any previously sprayed insecticides.

A storm will often leave standing water behind as well, which creates a breeding ground for mosquitoes.

It doesn't take very long for mosquitoes to breed, Rasgon said, so it wouldn't take very long after a storm for the insects to take over the area, nulling previous control efforts.

"Mosquito populations can rebound fairly quickly," Rasgon said.

But with little data on the subject, the direct impact of tropical systems on Zika is still unclear. More research on the subject is necessary, Rasgon said. It will depend on the size and strength of individual storms as well.

"There are other aspects to consider in the event of a hurricane including increased outdoor exposure and crowding that may increase the risk of infection," Patrick Wedlock, an infectious disease outbreak analyst at Ascel Bio, said.

Wedlock stressed that people should be vigilant about dumping any standing water and to continue to ward off mosquitoes by using repellants and wearing appropriate clothing.

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